AB0354 THERAPEUTIC DRUG MONITORING: PERFORMANCE OF THE FIRST LATERAL FLOW-BASED POINT OF CARE TEST FOR THE QUANTIFICATION OF INFLIXIMAB IN A FINGER PRICK
Authors: A. Ametzazurra, J. Pascual, L. Del Rio, A. Maguregui, D. Nagore, M. B. Ruiz-Argüello
Journal: Annals of the Rheumatic Diseases (2022)

Background Promonitor Quick IFX is a lateral flow test (LFT) for the quantification of infliximab (IFX) in human whole blood (finger prick or venous) or serum in 20 minutes. This LFT is based on a sandwich immunoassay to quantify either the reference IFX or biosimilars. Objectives The objective of this study was to perform the required analytical studies to establish the specifications of the product. Methods Clinical and Laboratory Standards Institute (CLSI) guidelines were followed for the evaluation of the analytical specifications of the LFT in whole blood and serum matrices: Linearity (EP-06-A), Detection capability (EP17-A2), Interfering substances (EP07, 3rd Edition) and Intermediate precision (EP05-A3). Results were obtained in combination with the automated portable reader PQreader. A Datamatrix provided with each Promonitor Quick IFX kit contains the calibration information required for the PQreader to measure the Control and Test lines and report the IFX concentration. Results The linear assay range was determined to be 1-58 µg/mL in whole-blood and 0.6-67 µg/mL in serum according to the processes indicated in the Package Insert. The Limit of Blank is 0.8 μg/mL, the Limit of Detection and Lower Limit of Quantification (LLoQ) are 1.1 μg/mL, and the Upper Limit of Quantification (ULoQ) is 15.4 μg/mL. There was no effect on assay performance when each of the following substances were added to samples with 0, 3, and 7 μg/mL of IFX: Haemoglobin (&gt;1000 mg/dL), Bilirubin (&gt;40 mg/dL), Triglycerides (&gt;1500 mg/dL), HAMA (160 AU/mL), Rheumatoid factor (200 IU/mL), EDTA (5.4 mg/mL), Heparin (51 U/mL), Citrate (11.4%), Vedolizumab (60 μg/mL) and Adalimumab (20.25 μg/mL). Repeatability and within-device precision results obtained for the positive samples are shown in Table 1. Table 1. IFX theoretical concentration (μg/mL) Whole blood samples Serum samples Mean observed IFX concentration (μg/mL) Repeatability Within-device precision Mean observed IFX concentration (μg/mL) Repeatability Within-device precision SD CV% SD CV% SD CV% SD CV% 3 3.2 0.6 18 0.8 25 3.6 0.5 15 0.6 17 7 7 1.3 18 1.7 24 8.3 1.4 16 1.8 21 10 9.8 1.8 18 2.7 28 10.9 1.8 16 2.3 21 The negative samples showed a negative result in all the measurements. Conclusion Promonitor Quick IFX is the first LFT available for true Point of Care testing of patients treated with IFX with just a finger prick sample. It provides quick turnaround time to facilitate therapeutic drug monitoring and aid immediate decision making in the doctor office or hospitals with an excellent analytical performance. Disclosure of Interests Amagoia Ametzazurra Employee of: Employee of Progenika Biopharma - Grifols, Javier Pascual Employee of: Employee of Progenika Biopharma - Grifols, Lorena Del Rio Employee of: Employee of Progenika Biopharma - Grifols, Ainara Maguregui Employee of: Employee of Progenika Biopharma - Grifols, Daniel Nagore Employee of: Employee of Progenika Biopharma - Grifols, M. Begoña Ruiz-Argüello Employee of: Employee of Progenika Biopharma - Grifols